1. Field of the Invention
This invention relates to a heteroscopic turbine, which is a turbine that uses microscopic or nanoscopic principles to generate macroscopic effects; more specifically, the invention relates to a heteroscopic turbine with a Knudsen number around 1.
2. Description of the Related Art
Molecules in air (and other gaseous matter) are in constant motion, continuously colliding with each other. This molecular motion is constantly occurring, even if the bulk velocity of the air is zero.
The speed of the molecules between collisions is the mean thermal velocity for the air. The average distance between collisions is the mean free path distance. The overall bulk velocity of the air is the air's transport velocity. Theoretically, the maximum transport velocity that can be imparted to an airflow is the mean thermal velocity of the underlying air molecules.
Several conventional apparatuses exist for generating a flow of air. Examples include fans and turbomolecular pumps.
Fans force air to flow in bulk with rotating fan blades. Even highly efficient fans cannot achieve very high transport velocities compared to the underlying molecular motion of the air. In particular, even good fans can only achieve transport velocities that are on the order of a hundredth to a thousandth of the mean thermal velocity of the air molecules.
Because high-velocity (i.e., comparable to mean thermal velocity) bulk air flow cannot be achieved with conventional fans, larger fans must be used to move significant amounts of air. As a result, fan size often becomes a limiting design factor for anything that requires airflow, cooling, or the like.
Another device for moving air (and other gaseous matter) is the turbomolecular pump. Turbomolecular pumps can be used as absorbers or consumers of air molecules. These pumps typically are used to draw molecules from a high vacuum environment in order to create an even “higher” vacuum.
Turbomolecular pumps use rotating turbine blades to select molecules from air. Molecules that randomly cross the tops of the blades are captured and whisked away.
In order for existing turbomolecular pumps to operate, collisions between air molecules must be avoided. If such collisions occur, the molecules can bounce away from the blades before they can be captured, defeating the operation of the pump.
Typical existing turbomolecular pumps use macroscopic turbine blades rotating at extremely high speeds, for example 75,000 RPM. These high speeds are used so that molecules that cross the path of the rotor blades do not have time to collide with other molecules before being whisked away.
Collisions are also prevented by ensuring that the mean free path distance for the molecules is not too small compared to the container or feed tube for the pump. The ratio between container or feed tube length and mean free path distance is the Knudsen number.
Typical existing turbomolecular pumps only operate effectively if the Knudsen number is no greater than approximately 10. This Knudsen number can only be achieved in a high vacuum, and then with only relatively small containers or feed tubes. Obviously, a significant air flow cannot be generated by pumping from a high vacuum through a small container or feed tube. As a consequence, existing turbomolecular pumps do not generate significant air flow.
All of these problems also exist when generating a flow from any other gas or gas mixture besides air.